if you want straight up advantage... get the audiotechnica ad500x and pair it up with a clip on mic. if you absolutely need surround sound get a xonar dg or u3 to go with it. if you wanted something with a bit more bass (which starts to take away advantage for footsteps slightly) check out the hd518.
the ad500x/700x/900x series are well known for giving excellent advantage in fps gaming due to a huge soundstage, good positional audio and not having much bass response which means hearing footsteps is easier.